1. Field of the invention
The present invention relates to a method and apparatus for cutting off roots of bean sprouts.
2. Description of the prior art
Roots of the bean sprouts harvested are recently cut off for improvement in their appearances and resultant increase in the commodity quality before the bean sprouts are bagged to be shipped. Japanese Patent Application Publication No. 10-136959 discloses an automated method of severing roots of bean sprouts. In the disclosed method, a conveyor for conveying harvested bean sprouts are provided with a first square bar mounted on an upper side thereof so as to be perpendicular to a conveying direction. A second square bar is disposed over the conveyor so as to be parallel to the first square bar. The second square bar is repeatedly moved at a speed higher than the conveyor is driven and then stopped, so that roots of bean sprouts are held between the two square bars thereby to be severed.
The roots of the bean sprouts are thus held between the square bars by horizontal relative movement of the conveyor and the second square bar to be severed in the disclosed method. In this method, however, the roots of the bean sprouts cannot smoothly be held between the two square bars. As a result, the disclosed method has a low severing efficiency and is accordingly unsuitable for severing the roots of the bean sprouts by a large amount at one time. Moreover, the low severing efficiency requires a long severing time, for which the bean sprouts tend to be rubbed against each other on the conveyor. As a result, the bean sprouts are easily bruised or spoiled and accordingly, the quality of the bean sprouts is reduced.
Therefore, an object of the present invention is to provide a method and apparatus for severing roots of bean sprouts, in which the roots of the bean sprouts can efficiently be severed with results of improvements in the productivity and quality while the damage of the bean sprouts is reduced during severing.
To achieve the object, the present invention provides a method of severing roots of bean sprouts comprising the steps of supplying bean sprouts onto a severing table having a number of severing slits each of which has such a width that a root of a bean sprout falls into each severing slit, sprinkling water over the severing table so that the roots of the bean sprouts on the severing table flow into the severing slits, and severing the roots of the bean sprouts fallen in the severing slits by a cutter blade. According to the above-described method, the roots of the bean sprouts can efficiently be severed while the damage of the bean sprouts is reduced. Consequently, both of the productivity and quality of the bean sprouts can be improved.
Either cutter blade or severing table may be moved. In a case where the cutter blade is moved, the cutter blade is preferably moved along the upper side of the severing table. In this construction, the cutter blade serves to feed the bean sprouts out of the severing table after the severing of the roots as well as to sever the roots of the bean sprouts. Consequently, both severing the roots and carrying the bean sprouts from the table can efficiently be performed by the movement of the cutter blade continuously. However the cutter blade may be moved along the underside of the severing table when the severing table has a small thickness.
The severing slits of the table may be formed by punching a metal plate, for example. Alternatively, the severing table may comprise a number of bar-shaped members having respective edges for severing the root of the bean sprout and arranged in parallel at an interval of a space substantially equal to the width of each severing slit. In this construction, the spaces between the bar-shaped members serve as the severing slits respectively. Consequently, the space between the bar-shaped members can be changed according to a type or size of the bean sprout whereupon the intervals of the severing slits can easily be adjusted.
When a flat cutter blade is disposed in parallel to the severing slits, the roots of the bean sprouts in the severing slits need to be simultaneously severed by a blade edge. Accordingly, since a load at the time of severance is increased, a driving power of an electric motor for driving the cutter blade needs to be increased accordingly. As a result, the size of the driving motor and an amount of electric power consumed are disadvantageously increased.
In view of the aforesaid problem, the cutter blade is preferably formed in such a zigzag shape that an edge thereof for severing the root of the bean sprout obliquely intersects the severing slits as seen from above. In this construction, the blade edge of the cutter blade obliquely intersects the edges of the severing slits when passing the severing slits. A point of intersection is moved along the edges of the severing slits with movement of the cutter blade. Accordingly, since the roots of the bean sprouts in the respective severing slits can gradually be severed, they can easily be severed and the driving power of the motor driving the cutter blade can be reduced. Consequently, reductions in the size of the driving motor and a consumption of electric power can be achieved.
The overall cutter blade may be formed into the zigzag shape. However, in the case where the upper edge of the cutter blade is zigzag, the bean sprouts are caught on the upper edge of the cutter blade at a high rate when the bean sprouts are supplied onto the severing table from over the cutter blade.
In view of the aforesaid problem, the cutter blade is preferably formed so that an inclination thereof relative to the severing slits is reduced from a lower side to an upper side, and the cutter blade preferably has a generally straightforward upper edge. In this construction, the rate at which the bean sprouts are caught on the upper edge of the cutter blade can be decreased.
The cutter blade preferably has an upper edge provided with slipping means for slipping the bean sprouts off. Consequently, the slipping means can further prevent the bean sprouts from being caught on the blade edge of the cutter blade.
When the cutter blade is moved only in the carrying direction, the bean sprouts are scraped up together on the severing table to be piled up. Roots of the bean sprouts located at an upper layer of the piled bean sprouts cannot sometimes be severed.
As a countermeasure, the cutter blade is preferably moved alternately repeatedly forward by a first predetermined distance and backward by a second predetermined distance, the second predetermined distance being shorter than the first predetermined distance. In this construction, the piled-up bean sprouts on the severing table are broken when the cutter blade is moved backward such that unsevered roots of the bean sprouts can be caused to flow into the severing slits. Consequently, the roots of the bean sprouts piled up on the severing table can uniformly be severed.
A plurality of the cutter blades are preferably disposed at a predetermined interval and each cutter blade is connected to a rotated chain. Since the cutter blades are driven by a single driving source, the structure of the driving system can be simplified.
The invention also provides an apparatus for severing roots of bean sprouts, comprising a severing table having a number of severing slits each of which has such a width that a root of a bean sprout falls into each severing slit, a cutter blade provided on the severing table, means for supplying bean sprouts onto the severing table, means for sprinkling water over the severing table, and cutter drive means for moving the cutter blade along an upper side of the severing table. Consequently, both of the productivity and quality of the bean sprouts can also be improved.